In recent years, dramatic improvement has been made in the performance of computers and touch input devices such as a tablet and a smartphone have become able to display three-dimensional (3D) images. The touch input devices of recent years can also perform various operations on a 3D image displayed on a screen such as enlargement, reduction, sliding, and rotation.
For example, Japanese Patent Application Laid-Open No. 2000-293711 discloses a personal computer including a mouse, a keyboard, and an auxiliary storage device with which a 3D display program is installed. The user executes this 3D display program in the personal computer and drags a 3D image by either mouse operation alone or mouse operation and keyboard operation in combination, to rotate the 3D image. This can facilitate the user to view a freely selected portion of the 3D image.
However, in the personal computer of the foregoing Japanese application, the user needs to simultaneously drag the 3D image and push a key provided in the mouse alone or pushing keys provided in the mouse and the keyboard. Hence the foregoing personal computer has a problem where the input operation is complex and is thus inconvenient for the user.
Accordingly, it is an object of the present invention to provide a touch input device capable of rotating an image by simple and intuitive input operation.